Interactions of Desmethoxyyangonin, a Secondary Metabolite from , with Human Monoamine Oxidase-A and Oxidase-B.

(Zingiberaceae), a medicinal plant of tropical rainforests, is used to treat snakebites and other injuries and also as a febrifuge, analgesic, antiemetic, antiulcer, and anticonvulsant. The dichloromethane extract of leaves showed potent inhibition of human monoamine oxidases- (MAOs-) A and B. Phytochemical studies yielded six known compounds, including pinostrobin , 4'-methyl ether sakuranetin , sakuranetin , pinostrobin chalcone , yashabushidiol A , and desmethoxyyangonin . Compound displayed about 30-fold higher affinity for MAO-B than MAO-A, with Ki values of 31 and 922 nM, respectively. Kinetic analysis of inhibition and equilibrium-dialysis dissociation assay of the enzyme-inhibitor complex showed reversible binding of desmethoxyyangonin with MAO-A and MAO-B. The binding interactions of compound in the active site of the MAO-A and MAO-B isoenzymes, investigated through molecular modeling algorithms, confirmed preferential binding of desmethoxyyangonin with MAO-B compared to MAO-A. Selective reversible inhibitors of MAO-B, like desmethoxyyangonin may have important therapeutic significance for the treatment of neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease.